The purpose is to devise experimental methods for obtaining morphological information about erythrocytes and platelets in suspension from light scattered or transmitted by the suspension. Of interest are cell shape, internal and surface structure, and size. Optical effects which might serve as bases of such methods are observed and accounted for in terms of light scattering theory. Of particular interest are experiments in which erythrocytes in saline and platelets in plasma oriented by stirring the suspension. Information about shape is obtained by comparing optical properties of partly oriented systems with those of the same system when randomly oriented. While information about cell shape might be obtained through microscopic examination, photometric methods have the advantage of providing information about many cells, high sensitivity, and relative immunity to effects of cell heterogeneity. They require no preparation of the sample and can be carried out on live systems during simultaneous measurements of other sorts. They can provide their information about morphological changes which in some cases are related to changes in rates of internal processes.